This invention relates to a hydraulic fluid tank assembly, and more particularly, to a hydraulic fluid tank assembly for use in hydraulic circuit for implement and that for transmission.
In the hydraulic circuit for implement of the kind specified which has heretofore been used, a fluid return conduit extending from hydraulic load devices is connected to the upper part of a hydraulic fluid tank, and a suction port formed near the bottom part of the tank is connected to a suction port of a pump, the delivery port of which is connected through a filter to the hydraulic load devices. Therefore, the dust such as metallic chips or particles produced by wear-down of the hydraulic load devices such as brake disks will directly enter the hydraulic fluid tank. Part of the dust will settle on the bottom of the tank, but major part of the dust is drawn into the pump thereby causing scratches or abnormal wear in the component parts of the pump.
Whilst, in the conventional hydraulic circuit for transmission, an oil pan of the transmission is provided with a strainer and the suction side of the pump is connected to the strainer and its delivery side is connected through a filter to the transmission. Therefore, the dust produced in the transmission such as metallic chips or particles due to wear-down of the brake disk and the gears will drop into the central part of the oil pan and settle in part on the bottom thereof, however, the major part of the dust will enter the strainer and is removed thereby to some degree and is then sent into the pump thereby causing scratches or abnormal wear in the component parts of the pump. Thus, in both the hydraulic circuits, dust tends to be sent into the respective pumps and therefore there occurs the aforementioned trouble.
Whilst, construction vehicles have a hydraulic circuit for implement and that for transmission which are separately provided and each of which has an independent hydraulic fluid tank. Therefore, such construction is disadvantageous in that a larger space is required for provision of hydraulic fluid tanks, the use of a larger amount of hydraulic fluid becomes necessary, and troublesome control of the amount of the hydraulic fluid is required.
To eliminate the above-mentioned disadvantage, it is considered to employ a hydraulic fluid tank for common use in both hydraulic circuits for implement and transmission. However, if the dust such as metallic chips or particles etc. produced in the hydraulic circuit for transmission is sent into the hydraulic circuit for implement, there is a possibility of occurrence of breaking of high pressure seals, and therefore the common use of the hydraulic fluid tank for both hydraulic circuits is in fact undesirable.